The research objective is to study the pathophysiology of compartment syndromes by correlating muscle compartment fluid pressure, as measured by the wick technique, with physical, anatomical, biochemical, histological, circulatory, and neurophysiological parameters. These basic correlates will be applied to clinical cases of compartment syndromes. Our pilot studies indicate: 1) compartment syndromes are probably not elicited by tourniquet occlusion alone, 2) infusion of fluid into canine muscle compartments elevates compartmental pressure, 3) Dexon wick material, suitable for clinical studies, responds well to fluid pressure dynamics, 4) dye injections portray muscle compartments as relatively closed spaces with small foramia for transit of vessels, nerves and tendons. The wick technique will be used to define the pressure/time relationships with respect to viability and function of muscle and nerve in experimental compartment syndromes. The wick technique is a simple, accurate, and reliable measurement of compartmental fluid pressure. Biochemical, histological, and functional studies will be undertake to develop definitive criteria for determination of muscle necrosis. Nerve viability and function will be assessed by conduction velocity measurements. Patients with tibial fractures, high tibial osteotomies, or suspected compartment syndromes from other causes will be monitored by the wick technique for compartmental fluid pressure. Patients with chronic compartment syndromes will be studied by the wick technique before and after exercise. Finally, the accumulation of these studies should yield sufficient data to permit the evaluation of the compartmental fluid pressure measurement as an objective criterion for decompressive fasciotomy in patients at risk.